This invention relates generally to controllers for printers such as laser printers, and more particularly the invention relates to a processor Controller for a printer which can be implemented in a very large scale integrated circuit (VLSIC) semiconductor chip.
A page printer controller operates under control of a host computer in providing the video signals for a printer such as a laser printer. The functions of transforming data to a display coordinate system, clipping objects to conform to an image window, and scaling the window to the viewpoint of the destination display device are discussed in U.S. Pat. No. 4,449,201 for "Geometric Processing System Utilizing Multiple Identical Processors" and in U.S. Pat. No. 4,648,045 for "High Speed Memory and Processor System for Raster Display," as applied to graphics display.
Disclosed in the above-referenced co-pending patent applications are a unique single chip RISC processor and a memory control unit operable therewith to permit multiprocessing capability. The present invention is directed to a printer controller architecture which can utilize the RISC processor architecture and interface with the memory-control unit. The controller includes peripheral components such as a printer video processor (PVP), UART ports, an I/O bus interface, a DMA controller, a firmware ROM, and memory interface. The major functions of the printer controller are to communicate with a host computer, transform data into image data (coordinate transformation, clipping, scaling, and rasterization) interface with other components of the print engine (e.g. laser printer), and run diagnostics. Known in the prior art is a single chip unit (Intel i860) including a RISC processor and special graphics hardware. However, the graphics hardware is outside of the RISC processor and not physically and functionally integrated therein.